package liulishuo;

import java.util.List;
import java.util.Scanner;

public class Didi {

	 public static void main(String[] args) {
	        Scanner mScanner = new Scanner(System.in);
	        int a = mScanner.nextInt();
	        int b = mScanner.nextInt();
	        int c = mScanner.nextInt();
	        String[] input_arr = new String[a+b+c];
	        for(int i = 0;i<input_arr.length;i++) {
	        	if(i<a) {
	        		input_arr[i] = "a";
	        	}else if(i>a-1 && i < a +b) {
	        		input_arr[i] = "b";
	        	}else {
	        		input_arr[i] = "c";
	        	}
	        	
	        }
	      
	   
	        mScanner.close();
	        int num = 0;
	        aa: for (int i = 0, j = 0; i < Math.pow(input_arr.length, input_arr.length); i++) {
	            String str = String.format("%0" + input_arr.length + "d", Long.parseLong(Integer.toString(i, input_arr.length)));
	            for (j = 0; j < str.length(); j++) {
	                if (str.replace(str.charAt(j) + "", "").length() != str.length() - 1) {
	                    continue aa;
	                }
	            } 
	            boolean A = false;
	            boolean B = false;
	            boolean C = false;
	           
	            look:
	            for (j = 0; j < input_arr.length; j++) {
	            	while(j<input_arr.length-1) {
	            		if(input_arr[Integer.parseInt(str.charAt(j) + "")] == input_arr[Integer.parseInt(str.charAt(j+1) + "")]) {
	            			break look;
	            		}else {
	            			j++;
	            		}
	            		
	            	}
	            	if(input_arr[j] == "a") A = true;
	            	if(input_arr[j] == "b") B = true;
	            	if(input_arr[j] == "c") C = true;
	            	num ++;
	            	//System.out.print(input_arr[Integer.parseInt(str.charAt(j) + "")]+(j==input_arr.length-1?"\n":" "));
	            	if(j==input_arr.length-1) {
	            		if(!(A&B&C)) {
	            			num --;
	            		}
	            	}
	            }
	           
	        }
	        System.out.print(num);
	    }

}
